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Percentage Calculator
Use this percentage calculator for discounts, sales tax estimates, markups, grade changes, price changes, and everyday percent math.
Updated May 2026No signup requiredBuilt for mobile
Calculator
How to use this calculator
- Enter your values in the calculator fields.
- Check that the units and percent formats match what the label asks for.
- Click Calculate to update the result.
- Use Reset Calculator to restore the starting example.
Formula or calculation method
X percent of Y = Y x X / 100.
X is what percent of Y = X / Y x 100.
Percent change = (new value - old value) / old value x 100.
Discount price = original price x (1 - discount percent / 100).
Worked example
A $75 item with a 20% discount has a discount of $15, so the sale price is $60.
Practical planning tips
- Sale prices and coupons
- Tips, tax, and markups
- Budget changes
- Grade percentages
- Comparing old and new values
Common mistakes to avoid
- Dividing by zero when the comparison value is 0
- Treating percentage points and percent change as the same thing
- Forgetting to convert 7.5% into 0.075 before manual math
FAQ
Percentage Calculator questions
Is this calculator exact?
It is a practical estimate based on the values you enter. Verify important decisions with the official source, lender, school, product label, or professional guidance when needed.
Why did I get an error?
The calculator checks for blank fields, invalid numbers, impossible negative values, and divide-by-zero situations. Review the message and adjust the input.
Can I use this calculator on my phone?
Yes. The inputs, buttons, and result cards are built to work on mobile screens.
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